1. Field of the Invention
This invention relates to an optical disc apparatus and method for controlling turntable rotation, and more particularly to an optical disc apparatus having a turntable arranged to mount thereon an optical disc, such as CD-ROM, CD-RW, DVD and so on, and having a vibration suppressing function, such as with a balancer, and a method for controlling turntable rotation.
2. Prior Art
The present applicant has disclosed, in Japanese Utility Model Registration Application No. H9-6240, one example of a turntable having a vibration suppressing function. This turntable has a balancer accommodated within an annular space formed coaxially to a rotation center of its main body. During reproduction with a disc, the balancer automatically comes to rest at a predetermined position in response to an eccentricity of the turntable gravity center, thereby keeping the turntable in balanced rotation and hence suppressing against vibrations.
In the above-mentioned turntable, the optimal position of the balancer is different depending upon rotation speed of the turntable. On the other hand, the balancer once brought into rest will not readily move even if the turntable rotation speed is varied. Accordingly, where the rotation speed of the turntable is increased from a speed of 4 times the normal speed up to a speed of 32 times the normal speed, the turntable rotates at the 32-times speed in spite that the balancer remains resting at an optimal position for the 4-times speed. Due to this, there has been a difficulty in suppressing vibrations to a sufficient extent when the turntable is rotated at the 32-times speed.
It is therefore a primary object of the present invention to provide a method for controlling turntable rotation by which vibration is sufficiently suppressed at every rotation speed even where the rotation speed of the turntable is varied.
It is another primary object of the present invention to provide an optical disc apparatus which is capable of sufficiently suppressing vibration at every rotation speed even where the rotation speed of the turntable is varied.
An optical disc apparatus according to the present invention, comprises: a turntable for mounting an optical disc thereon; an annular space formed coaxially to a rotation center of the turntable; a balancer accommodated movable within the space; a first rotating means which causes the turntable to rotate at a first rotation speed to thereby cause the balancer to rest at a first position within the space; a decelerating means which decelerate the turntable to cause acceleration between the turntable and the balancer to thereby release the balancer from resting; and a second rotating means which causes the turntable to rotate at a second rotation speed higher than the first rotation speed to thereby cause the balancer to rest at a second position within the space.
A control method according to the present invention, comprises the steps of: (a) a step of rotating the turntable at a first rotation speed to rest the balancer at a first position within the space; (b) a step of decelerating the turntable to cause acceleration between the turntable and the balancer releasing the balancer from resting; and (c) a step of rotating the turntable at a second rotation speed higher than the first rotation speed to bring the balancer to rest at a second position within the space.
In this optical disc or control method, the turntable is rotated at the first rotating speed to cause the balancer to rest at an optimal position for the first rotation speed. Then brake is applied to a motor to decelerate the turntable causing acceleration between the turntable and the balancer and releasing the balancer from resting. Thereafter the turntable is rotated at the second rotation speed higher than the first rotation speed to bring the balancer to rest at an optimal position for the second rotation speed. Therefore, the turntable can be kept in balanced rotation for both first and second rotation speeds.
An optical disc apparatus according to the present invention, comprises: a turntable for mounting an optical disc thereon; an annular space formed coaxially to a rotation center of the turntable; a balancer accommodated movable within the space; a first rotating means which causes the turntable to rotate at a first rotation speed to thereby cause the balancer to rest at a first position within the space; and a second rotating means which causes the turntable to rotate at a second rotation speed higher than a rotation speed at which the balancer is released from resting but is lower than a first rotation speed.
A control method according to the present invention, comprises the steps of: (a) a step of rotating the turntable at a first rotation speed to cause the balancer to rest at a predetermined position within the space; and (b) a step of rotating the turntable at a third rotation speed that is higher than a second rotation speed at which the balancer is released from being rested but is lower than the first rotation speed.
In this other optical disc or control method, the turntable is rotated at the first rotation speed to cause the balancer to rest, and then the turntable is rotated at the third rotation speed lower than the first rotation speed. In a state that the balancer is rested at an optimal position for the first rotation speed, no vibration occurs in the turntable rotating at the third rotation speed lower than the first rotation speed.
The above described objects and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.